C3
1, \(=>Idm1=\dfrac{Pdm1}{Udm1}=\dfrac{6}{12}=0,5A,R1=\dfrac{Udm1^2}{Pdm1}=24\left(om\right)\)
\(=>Idm2=\dfrac{Pdm2}{Udm2}=\dfrac{4}{12}=\dfrac{1}{3}A,R2=\dfrac{Udm2^2}{Pdm2}=36\left(ôm\right)\)
2. K mở =>R1 nt R2
a,\(=>Im=I1=I2=\dfrac{Umn}{R1+R2}=0,4A\)
b, \(=>U1=I1.R1=9,6V=>U2=I2.R2=14,4V\)
\(=>P1=U1.I1=3,84W,P2=U2.I2=5,76W\)
3,khi khóa K đóng =>(Rb // R2) nt R1
khi đèn sáng bình thường \(=>Ib=I1-I2=0,5-\dfrac{1}{3}=\dfrac{1}{6}A\)
\(=>Ub=U-U1=24-I1.R1=24-24.0,5=12V\)
\(=>Rb=\dfrac{Ub}{Ib}=72\left(om\right)=Rbc\)
\(=>Rac=Rab-Rbc=150-72=78=>\dfrac{Rac}{Rbc}=\dfrac{13}{12}=>AC=\dfrac{13}{12}BC\)
vậy phải dịch con chạy C sao cho.....
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